
Just took a short trip to Foochow and had been fascinated with the Hok-ciu language. Although more heavily influenced by Middle Chinese than Hokkien, Hokciu is probably 100 times harder to learn (at least for me). Sandhi is not limited to tones--everything (inc consonants and vowels) changes in such a complicated manner and --according to some online linguistic enthusiasts from Foochow-- "there seems to be no sandhi rules".
The status of the language is very bad, perhaps (partly) due to its difficulty. Out of ten people I knew from Foochow back in college (now in their mid-twenties), only two could speak it. During this trip I visited a close friend of mine. His family and family friends spoke exclusively in Foochow; he grew up in such environment (for 18 years) but couldn't even make out a complete sentence in Foochow. This has been unimaginable to me, as I always believe that young children are able to acquire language without being taught explicitly. And he is definitely not an exception (he "acquired" fluent Cantonese in Hong Kong within two years without really putting much effort).
Although my exposure to the language was really brief, I could make out some words that were similar to Hokkien, like 行 囝 kiang, 目睭 moi-ciu, 厝 chuo. It seems to be almost certain that the two shared the same origin but it is unclear to me when and how they diverged.